GEOCHEMICAL CHARACTERISTICS OF THE SURFACE SEDIMENTS IN THE MINJIANG RIVER ESTUARY AND ITS ADJACENT SEA AREA

Minjiang River is the major river in the coast area of Southeast China and it is the third largest in terms of annual runoff over the country. According to XRF analysis of 25 sediment samples collected from the lower reaches of the Minjiang River and the adjacent waters of the Estuary, the sediments are characterized by a high SiO₂, lower Al₂O₃ of components. The main detrital minerals of samples are quartz, plagioclase, orthoclase, muscovite and chlorite. Based on SiO₂ content, the sediments composition of Minjiang River is closer to quartz sandstone, and different from the shallow sea sediments and distinct from the Yellow River, Yangtze River and Pearl River. From upper to sea, the SiO₂ content is decreasing while Al₂O₃ increasing. It is reckoned that the topography and hydrodynamic conditions control the distribution of sediment granularity, which will further effects sediment component distribution. Moreover, human activities impact on the sediments of Minhou section and Peigang to Majiang section of the river cannot be neglected. The sediments of Minjiang River exhibit a reasonable correlation between different components which could be the combined effects of the source characteristics of the Minjiang River, the hydrodynamic conditions, the transport distance, as well as physical and chemical conditions and biological transformation of sediments.